Eocene Basins. 237 



Eocene rocks lie sometimes on upper beds of Chalk, 

 and sometimes on beds lower in the series. They are, 

 therefore, highly unconformable to each other, and this 

 alone marks a great interval of time, unrepresented in 

 England by the deposition of strata. The subject is 

 evidently connected with the nearly total break in 

 succession of evident species between the Cretaceous 

 and Eocene formations ; for, great continental areas 

 of Chalk were heaved above the sea and remained 

 as dry land for a period of time so long, that, when 

 they were again submerged, the life of Cretaceous 

 times had mostly been remodelled by slow evolution, 

 and newer forms, in time became the legitimate suc- 

 cessors of their long-buried ancestors. 



When critically examined, it soon becomes evident 

 that the strata of the basins mentioned above were 

 not originally deposited in two distinct basin-shaped 

 hollows, but that they were once united, and formed 

 one great area of Eocene age. Long after, a disturb- 

 ance of the Secondary and Lower Tertiary strata took 

 place, which threw them into broad anticlinal and 

 synclinal curves. One long and broad anticlinal curve 

 passes along the Wealden area from east to west, and 

 still further on through part of the Chalk. South of this 

 we find the synclinal curve of the Hampshire basin, 

 bounded on the south by the Cretaceous strata of the 

 Isles of Wight and Purbeck, and on the north by the 

 Chalk of the Salisbury, Winchester, and Brighton area, 

 while north of the Weald, the Eocene rocks of the 

 London basin bounded by Chalk lie in a similar 

 synclinal curve, broad at its east or seaward end, and 

 narrow at its western end towards Marlborough. When 

 still more closely examined, it is found that many beds 

 of our Eocene strata were deposited in fresh and in 



